The mice were divided into ten groups. They were sacrificed on 1 st, 5 th, 10 th, 15 th, 20th, 25 th, 30 th, 35 th, 40 th day after birth, and one group was sacrificed after maturation. The murine ovaries were studied by morphological and histochemical methods. On day 1 after birth,there were many primorial follicles and a few stroma in the ovaries. After day 5, follicles began to develop: follicular cells became columnar instead of being simple squamous. The follicular theca was formed on day 10, and follicular cells developed into 2 or 3 layers, named membrana granulosa. Zona pellucida formed. Granulosa cell's mitotic devisions result in six layers of cells, and interstitial glands appeared. From day 20 to maturation, all of the developed interstitial glands, secondary follicles, and atresic follicles could be found. 3-β-HSDH in the theca interna were showed on day 10, then appeared in membrana granulosa, interstitial glands and corpora luteum. Moreovers the action of 3-β-HSDH in the theca interna and interstitial glands increased with the growth. The distribution of lipiole was as same as that of 3-β-HSDH. Alkaline phosphatase locatized in theca interna on day 10 then increased gradually. LNAase, acidic phosphatase and glycogen distributed very wide in overies, and action increased with the growth.
